From Dedicated Redundant Subcarriers to Distributed Redundancy in UW-OFDM

Unique word orthogonal frequency division multiplexing (UW-OFDM) is based on introducing redundancy, either on dedicated redundant subcarriers leading to systematically encoded UW-OFDM, or spread over the entire bandwidth resulting in the non-systematically encoded UW-OFDM concept. The waveform design of the latter has originally been optimized by incorporating transmitter and receiver processing steps, while the systematic approach primarily focuses on the redundant transmit energy minimization. This work closes the gap between both by introducing a design procedure for non-systematically encoded UW-OFDM that is also predicated on redundant energy arguments. Furthermore, this approach provides a simple way to increase the bandwidth efficiency.